Flat panel display technology is evolving fast, with increasing size of flat panel displays being produced. Exposure using an objective with a large field of view (FoV) can effectively increase manufacturing yield. However, FoV enlargement for an objective optical system will raise difficulties in design, manufacturing and other aspects. A required large FoV can be alternatively achieved by putting together equally-sized FoVs of several proper objective lenses that are arranged in a certain style. The number of the used objectives is determined by the size of the required FoV. This approach can meet the needs for large FoVs, while reducing the optical processing and manufacturing difficulties and providing high compatibility and flexibility.
However, in the above approach, imaging locations of the individual objectives may deviate from their supposed positions due to their performance and assembly tolerances. In addition, the large-sized mask may undergo gravity-caused deformations which may lead to deviations in surface of the photosensitive substrate. For these reasons, each of the used objectives is provided with a separate adjustment apparatus for tuning its FoV to where it is supposed to be so as to ensure high quality of the combined FoV.
A scanning exposure device equipped with multiple projection optical systems that generate projection fields stepping forward by predetermined amounts of displacement in the scanning direction, with end portions of neighboring fields overlapping each other in a direction orthogonal to the scanning direction, is called a multi-lens scanning exposure device. With such a multi-lens scanning exposure device, the mask is illuminated through multiple illumination slits and is scanned together with the photosensitive substrate simultaneously in a direction orthogonal to the arrangement direction of the illumination slits so that the multiple projection optical systems corresponding to the respective illumination slits expose a pattern on the mask onto the photosensitive substrate.
Patent Application Publication No. JP2005331694A discloses an exposure device capable of focal plane adjustment by means of translating right-angle reflectors or a group of wedge plates. Focal plane adjustment by translation of the right-angle reflectors will lead to changes in the optimum positions for image and object planes and hence decrease in focal depth. In the approach using vertical translation of the wedge plates for focal plane adjustment, the distance between the two wedge plates will be changed resulting in translational displacement of the image plane in the Y-direction. This translation needs to be offset by means of rotation of parallel plates. Horizontal shifts of the image are enabled by rotating the two parallel plates respectively about the X- and Y-directions. Magnification adjustment is made possible by moving any of three half-lenses that constitute an afocal optical system, but however, at the same time, introduces a change in the focal plane which needs to be offset using the focal adjustment system.
Patent Application Publication No. US20020005940 discloses an exposure device capable of magnification adjustment by axial translation of an afocal optical system consisting of two lenses, and of focal plane adjustment by translation of an afocal optical system consisting of three lenses. The magnification adjustment by the axial translation of the afocal optical system consisting of the two lenses introduces changes in the focal plane, whilst the focal plane adjustment by translation based on the afocal optical system consisting of the three lenses causes changes in magnification. Therefore, either of the focal plane adjustment and magnification adjustment involves both of the devices for performing these tasks.
Therefore, magnification adjustment and focal plane adjustment are currently carried out using separate adjustment devices and introduces undesirable crosstalk that needs to be compensated for with other device(s). This leads to a cumbersome adjustment process.